The dislocation microstructure after tensile deformation for a Ni-base single-crystal superalloy was studied by transmission electron microscopy. The samples were strained to fracture between room temperature and 1273K. It was found that, for deformation at intermediate temperatures, the dislocation microstructure was inhomogeneous due to the formation of dislocation concentrations with high-density tangling. These dislocation concentrations lie mainly along <100> or <110> directions, and extended over a length of a few micrometers. In addition, the structure of dislocation networks at the γ/γ' interfaces formed at high temperature was also studied. Although previous studies have proposed basic configurations for these dislocation networks, the nature of a dislocation segment along the <010> direction had not been resolved. High-resolution electron microscopy was used here to study these dislocation networks. It was found that most of these segments were actually composed of 2 pairs of a/2<110> dislocations with an average spacing of 8.5nm, while only a few of them were composed of single-line a<100> dislocations.

The Dislocation Microstructure of a Nickel-Base Single-Crystal Superalloy after Tensile Fracture. Z.P.Luo, Z.T.Wu, D.J.Miller: Materials Science and Engineering A, 2003, 354[1-2], 358-68